1. Field of the Invention
The present invention relates to a process for the emulsion polymerization of one or more olefins by reacting a quinoid compound of the formula Ia or Ib or a mixture of at least two of the compounds Ia or Ib

where R in each case is one or more of the following radicals:
hydrogen
halogen
nitrile
C1-C12-alkyl groups, C1-C12-alkoxy groups, C7-C15-aralkyl groups, C6-C14-aryl groups, unsubstituted or substituted by: C1-C12-alkl groups, halogens, C1-C12-alkoxy groups, C3-C12-cycloalkyl groups, C1-C12-thioether groups, if appropriate also carboxyl groups or sulfo groups present in the form of their salts, and amino groups with hydrogen and/or C1-C12-alkyl radicals,
amino groups NR1R2, where R1 and R2 together or separately are hydrogen, C1-C12-alkyl groups, C7-C15-aralkyl radicals and C6-C14-aryl groups and may additionally also form a saturated or unsaturated 5- to 10-membered ring, unsubstituted or substituted by: C1-C12-alkyl groups, halogens, C1-C12-alkoxy groups, C3-C12-cycloalkyl groups, C1-C12-thioether groups, if appropriate also carboxyl groups or sulfo groups present in the form of their salts, and amino groups with hydrogen and/or C1-C12-alkyl radicals,
it being possible for identical or different compounds of the formulae Ia and Ib if appropriate also to be bridged by one or more C1-C12-alkylene bridges, C2-C12-alkylated azo bridges or bridges of the formula II

where Y is silicon or germanium and R3 and R4 are hydrogen and/or a C1-C12-alkyl group,
with a phosphine compound,
and with a metal compound of the formula M(L2)2, M(L2)2(L1)z1 or M(L1)z2,
where
M is a transition metal of groups 7 to 10 of the Periodic Table of the Elements,
L1 is a phosphane (R5)xPH3-x or amine (R5)xNH3-x having identical or different radicals R5, an ether (R5)2O, water, an alcohol (R5)OH, pyridine, a pyridine derivative of the formula C5H5-x(R5)xN, carbon monoxide, C1-C12-alkylnitrile, C6-C14-arylnitrile or an ethylenically unsaturated double bond system, where x is an integer from 0 to 3,
R5 is hydrogen, a C1-C12-alkyl group, which in turn may be substituted by O(C1-C6-alkyl) or N—(C1-C6-alkyl)2 groups, a C3-C12-cycloalkyl group, a C7-C15-aralkyl radical or a C6-C14-aryl group,
L2 is a halide ion, an amide anion (R6)yNH□2-y, where y is an integer from 0 to 2 and R6 is a C1-C12-alkyl group, and furthermore a C1-C6-alkyl anion, allyl anion, benzyl anion or aryl anion, where L1 and L2 may be linked to one another by one or more covalent bonds,
z1 is an integer from 1 to 4, and
z2 is an integer from 1 to 6,
and subsequently using the reaction product for the polymerization or copolymerization of olefins in water or in a solvent mixture which contains at least 50% by weight of water, in the presence of an emulsifier and optionally in the presence of an activator, wherein the phosphine compound used is either a compound III of the formula (R′)aPH3-a, where R′ is a C1-C12-alkyl group, C3-C12-cycloalkyl group, C7-C15-aralkyl group or C6-C14-aryl group, which is substituted by at least one polar radical P, the polar radical P being selected from the group consisting of                hydroxyl, carboxyl, sulfo, hydroxysulfonyloxy or phosphono groups and the possible alkali metal, alkaline earth metal and/or ammonium salts thereof,        alkanolammonium, pyridinium, imidazolinium, oxazolinium, morpholinium, thiazolinium, quinolinium, isoquinolinium, tropylium, sulfonium, guanidinium and phosphonium groups and ammonium groups of the formula IV        —N⊕R7R8R9 IV, where        R7, R8 and R9, independently of one another, are hydrogen or a C1-C12-alkyl group,        or        a group of the formula V, VI or VII-(EO)k—(PO)l—R10   V,-(PO)l-(EO)k—R10   VI,-(EO)k/POl)—R10   VII, where        EO is a —CH2—CH2—O— group,        PO is a —CH2—CH(CH3)—O— or a —CH(CH3)—CH2—O— group,        k and l are numerical values from 0 to 50, but k and l are not simultaneously 0,        R10 is hydrogen, a C1-C12-alkyl group or a sulfo group or the corresponding alkali metal, alkaline earth metal and/or ammonium salt thereof, and        
a is 1,2 or 3,
and/or a diphosphine compound VIII of the formula (R′)bPH2-b-G-PR2″, where R″ is hydrogen or has the same meaning as R′, G is a C1-C12-alkylene group, C3-C12-cycloalkylene group, C7-C15-aralkylene group or C6-C14-arylene group, and
b is 1 or 2.
Isolation and purification of the complex formed in situ (reaction product of metal compound, phosphine compound and quinoid compound) are dispensed with.
2. Description of the Background
An activator is optionally used for the novel process. Furthermore, this invention relates to dispersions of polyolefins, for example polyethylene and ethylene copolymers in water, and the use of the novel aqueous dispersions in paper applications and textile and leather applications, for the production of molded foams, carpet backing coatings and pharmaceutical formulations and as a component in adhesives, sealing compounds, plastics renders, coating materials and paints.
Aqueous dispersions of polymers are utilized commercially in numerous applications which differ very greatly. Examples are paper applications (coating and surface sizing), raw materials for paints and finishes, adhesive raw materials (including contact adhesives), textile and leather applications, in construction chemistry, molded foams (mattresses, carpet backing coatings) and for medical and pharmaceutical products, for example as binders for preparations. A summary is to be found in D. Distler (Editor), Wäβrige Polymerdispersionen, Wiley-VCH Verlag, 1st Edition, 1999.
It has been difficult to date to prepare aqueous dispersions of polyolefins. However, it would be desirable to be able to provide such aqueous dispersions of polyolefins because the monomers, such as ethylene or propylene, are very advantageous from economic points of view.
The conventional process for the preparation of such aqueous dispersions from corresponding olefins make use either of free radical high-pressure polymerization or of the preparation of secondary dispersions.
These processes therefore have disadvantages. The free radical polymerization processes require extremely high pressures, they are limited on the industrial scale to ethylene and ethylene copolymers, and the required apparatuses are very expensive to procure and maintain. The other possibility consists in first polymerizing ethylene in any desired process and then preparing a secondary dispersion, as described in U.S. Pat. No. 5,574,091. This method is a multistage process and therefore very complicated.
It is therefore desirable to polymerize olefins, for example ethylene or propylene, under the conditions of emulsion polymerization, and to prepare the required dispersion in one step from the corresponding olefin. Moreover, emulsion polymerization processes very generally have the advantage that they give polymers having high molar masses, the removal of heat being readily controlled as a result of the process. Finally, reactions in aqueous systems very generally are of interest because water is a cheap and environmentally friendly reaction medium.
Processes presented to date for the emulsion polymerization of olefins, such as ethylene or propylene, still require improvement. The problem lies in general in the catalyst required for the polymerization of these olefins.
Owing to the considerable commercial importance of polyolefins, the search for improved polymerization processes continues to be of great importance.
A good overview of the prior art on the polymerization of olefins in an aqueous medium, in particular with the use of polymerization catalysts prepared in situ, is given by the non-prior-published Patent Application with Application No. 10234005.6, filed by the Applicant at the German Patent and Trademark Office. The subject of this Application, which is hereby incorporated by reference, is the broad use of special quinoid compounds, usually phosphine or diphosphine compounds and especially transition metal compounds, for the in situ preparation of polymerization catalysts and the use thereof for the polymerization of olefins in an aqueous medium. The in situ catalysts mentioned in the description as being preferred and used in the examples were prepared using 2,3,5,6-tetrachloro-para-benzoquinone or 2,3,5,6-tetrabrom-para-benzoquinone and triphenylphosphine as the ligand compound. However, the use of very poorly water-soluble organic solvents, for example hexadecane, in the preparation of the in situ catalysts is not completely satisfactory. Also unsatisfactory is the fact that the in situ catalysts present as organic solutions are subjected, before being brought into contact with the olefin, to a treatment which converts the organic catalyst solutions into oil-in-water miniemulsions.